Traditionally, automotive internal combustion engine design has evolved for application to vehicles with rear wheel drive and longitudinally mounted engines. The advent of front wheel drive vehicles led to the use of the traditional engine designs with minimal modifications for transverse mounting. For the oil return system, the oil pump for the longitudinally mounted engine has an oil intake near the rear of the oil pan. During vehicle forward acceleration the pool of oil in the pan surges to the rear of the pan so that the intake will be well supplied with oil. During braking the deceleration moves the oil toward the front of the pan such that the intake is no longer supplied with oil. Similarly, braking while turning at or about 1.5 G's (approximately 45 degree turns) may also expose the oil intake such that oil flow in the engine is disrupted.
Some front wheel drive vehicles with transversely mounted engines have the same oil pickup system as described above with the intake favoring the “rear” or left end of the pan. As shown in FIG. 1, the oil pan 110 contains an oil pump 112 which is attached to the engine, not shown, by a support 114, an oil intake 116 attached to the pump, and a windage baffle 118. A pool of oil 120 in the pan assumes a position determined by gravity and other forces. Such vehicles may experience a reduction of oil intake efficiency during aggressive left turns. This occurs because during the left turn the oil rushes to the front of the oil pan (front of the engine and toward the right side of the vehicle), as shown in FIG. 1, and no longer leaves the oil intake fully submerged in oil; then some air is entrained in the oil which is drawn into the oil pump—risking the loss of pump prime, bearing lubrication loss, and engine failure. The actual reduction in efficiency is a function of the G force on the oil. High performance vehicles can develop high turning acceleration on the order of 0.85 G's and this could result in the surface of the oil tilting at a 40° angle. Of course less severe turning acceleration results in a smaller angle.
A factor in the oil flow management in an oil pan is the windage baffle 118 which is a generally horizontal sheet of metal spaced from the side walls of the pan (with fixed openings at the sides as well as front and rear). The windage baffle 118 is interposed between the rapidly moving engine parts and the pool of oil 120 to prevent air currents from whipping up the oil and causing aeration. The windage baffle may also vacuum up oil and return the oil to the oil pan as aerated. Some of the oil returning to the pan from the engine runs down the sides of the crankcase past the baffle and some drips onto the baffle and runs over the edge to the bottom of the pan. When oil surges onto the top surface of the baffle 18 during a turn, the horizontal baffle impedes the return of the oil to the vicinity of the intake.